Searches for low-mass exoplanets would clearly benefit when some practically measurable quantities were identified that could be used to correct short-term excursions in apparent stellar radial velocity. A considerable effort has been made in studying the Sun as a star and in searching for statistical relations between various parameters of solar and stellar variability, including work by [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]}, [10]}, [11]} and [12]}, and references therein. These studies used various statistical approaches to search for possible correlations and empirical proxies for radial-velocity fluctuations. Considerations of other spectral types include [13]} and [14]}, [15]}, [16]}.
